1. Field of the Invention
This invention generally relates to engine auxiliary starting devices of the type mounted in an outer vent control system of an internal combustion engine, and more particularly to an engine auxiliary starting device which leads fuel evaporative gases, which are produced in a float chamber at a high temperature, to a canister, thereby preventing the fuel evaporative gases from being discharged into the atmosphere after the engine starts.
2. Background of the Prior Art
Auxiliary devices of the type to which the present invention is directed are particularly well adapted for use in an outer vent control system of an automotive internal combustion engine. When the engine is stopped after reading a high temperature, the gasoline within the engine will evaporate due to the high temperature, such that the fuel will become rich due to the fuel evaporative gases. Therefore, it will be difficult to start the engine again.
FIG. 1 shows a conventional engine auxiliary starting device installed in the outer vent control system, wherein fuel evaporative gases discharged from a carburetor 1 flow into a float chamber 2 and reach a canister 5, through a thermal responsive valve 3 and an electromagnetic valve 4, in which fuel evaporative gases are condensed and sent to a fuel tank.
The electromagnetic valve 4 is kept closed during engine starting and is opened once the engine stops. The thermal responsive valve 3 is kept closed at an ambient temperature below 50.degree. C. and is opened at an ambient temperature greater than 50.degree. C. Therefore, when the ambient temperature is more than 50.degree. C. after the engine stops, fuel evaporative gases discharged from the float chamber 2 flow into the canister 5 through the thermal responsive valve 3 and the electromagnetic valve 4.
The predetermined temperature at which the thermal responsive valve 3 will operate is determined by actually surveying the relation between the ambient temperature of the thermal responsive valve 3 and the float chamber 2.
However, as shown in FIG. 2, there is a difference in the change of temperature between the thermal responsive valve and the float chamber after the engine stops. Furthermore, the positions of the float chamber 2 and the thermal responsive valve 3 are kept separate from one another, and there is a temperature hysteresis produced during operation of the thermal responsive valve 3 since a bimetallic disc is used as a thermal detective means.
Therefore, the time period of opening of the thermal responsive valve 3 is maintained longer than is necessary and also the fuel evaporative gases become too lean or weak because the canister 5 is connected with atmosphere during engine stopping. Therefore, the performance of engine starting after the engine has been stopped for a long period of time will deteriorate and the fuel consumption will increase.